The subject matter disclosed herein relates generally to cryogenically cooled magnetic resonance imaging (MRI) systems, and more particularly to systems and methods for cooling the magnet coils of the MRI systems.
In superconducting coil MRI systems, the coils forming the superconducting magnets are typically cryogenically cooled using a helium vessel. In these conventional MRI systems, the superconducting coils are cooled in a bath of liquid Helium (He), such that the coils are immersed in the liquid He. This cooling arrangement requires the use of an extremely large high pressure vessel that contains a significant amount of liquid He (e.g., 1500-2000 liters of liquid He). The resulting structure is not only expensive to manufacture, but heavy.
Additionally, in some instances the helium vessel may not be completely filled, such as to save cost. In this situation, portions of the wires forming the coils of the MRI superconducting magnet will be exposed to gas instead of the cooling liquid He. Accordingly, the likelihood of instability and a possible quench event increases. During quench events, the liquid He in these systems can boil-off, wherein the boiled-off helium escapes from the cryogen bath in which the magnet coils are immersed. Each quench, followed by a re-fill and re-ramp of the magnet, is an expensive and time consuming event.
Thus, a significant amount of liquid He is needed in conventional MRI systems. This large amount of He is needed not only to fill the large helium vessel, but increases with any subsequent re-fills.